A gas turbine includes a compressor which compresses outside air and generates compressed air, a combustor which mixes fuel with the compressed air, combusts the mixture, and generates combustion gas, and a turbine which has a rotor rotated by the combustion gas. The rotor includes a rotor main body which extends in an axial direction parallel to a rotational axis with the rotational axis as the center, and a plurality of blade stages which are fixed to the outer circumference of the rotor main body and are aligned in the axial direction. The combustion gas passing through the final blade stage is discharged to the atmosphere through the inside of the exhaust casing, the inside of the exhaust chamber, and the inside of the exhaust duct as exhaust gas.
In a gas turbine disclosed in Patent Document 1 below, the exhaust casing is formed by a cylindrical exhaust casing wall with the rotational axis of the rotor as the center. The exhaust chamber is formed by an exhaust chamber support which is connected on the downstream side of the exhaust casing wall and an exhaust chamber wall. A cylindrical external diffuser and a cylindrical internal diffuser are provided on the inner side in the radial direction of the exhaust casing wall and the exhaust chamber support with the rotational axis of the rotor as the center. The internal diffuser is disposed inside the external diffuser with an internal therebetween in the radial direction. An exhaust channel of the combustion gas is formed between the external diffuser and the internal diffuser.
A sealing device is provided on the downstream end of the exhaust casing wall and the upstream end of the exhaust chamber support. The sealing device which is provided on the downstream of the exhaust casing wall is a device which seals between the exhaust channel and the outside space between the exhaust casing wall and the external diffuser disposed in the inner side in the radial direction of the exhaust casing wall. The sealing device which is provided on the exhaust channel end of the exhaust chamber support is a device which seals between the exhaust channel and the outside space between the exhaust chamber support and the external diffuser disposed in the inner side in the radial direction of the exhaust chamber support.
Each sealing device includes two seal plates which are disposed with an interval therebetween in the axial direction and a spacer which maintains the mutual interval in the axial direction between the two seal plates.